Image credit: The New Solar System, via Windows to the Universe at http://www.windows.ucar.edu/ at the University Corporation for Atmospheric Research (UCAR).

“I have announced this star as a comet, but since it is not accompanied by any nebulosity and, further, since its movement is so slow and rather uniform, it has occurred to me several times that it might be something better than a comet. But I have been careful not to advance this supposition to the public.” –Giuseppe Piazzi

So it begins again: the neverending debate about who gets to be a planet and who doesn’t. Everyone can bring their own interpretation of the science to the table — and everyone has their own preferred naming scheme — but when I think about the Solar System, I try to think about it in the context of all star systems.

Believe it or not, as far as we’re able to tell, they all have some very important things in common.

Image credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration. Click for an incredible experience!

One is that — in the grand scheme of things — all star systems are intimately connected in the sense that no star, as far as we can tell, is ever born in true isolation. Large molecular cloud complexes eventually undergo gravitational collapse, forming large numbers of stars all at once, anywhere from hundreds to tens of millions of stars in a single cluster! Although the stars that form in these clusters will come in a wide variety of sizes and masses, they all have many similar properties, including the same rough proportion of heavy elements to one another.

But with the exception of the highest mass, globular star clusters, these large groupings of stars don’t last very long.

Image credit: Fred Espenak of http://astropixels.com/, of the Hyades cluster.

The closest star cluster to us, the Hyades (just 151 light-years away), is in the process of dissociating, where repeated gravitational encounters with (or within) the disk of our galaxy drive the individual stars making a star cluster apart. Our Sun, itself, was very likely once a part of a similar cluster of thousands of stars, born some 4.5 billion years ago in one of our galaxy’s ancient star-forming regions!

But when they do form, these stars aren’t the only things that come about.

Image credit: C.R. O’Dell/Rice University; NASA.

What will eventually become each star, to the best of our knowledge, starts out as a triaxial ellipsoid, undergoes gravitational collapse, forming a star (or stars) near the central region, pancakes along the shortest axis, and winds up forming a protoplanetary disk around the central protostar. The entire complex rotates with some angular momentum, and the protoplanetary disk itself typically lasts for a few million years.

Image credit: NASA / FUSE / Lynette Cook.

During this time, there are a few physically interesting things fighting for superiority.

The young star (or stars) are shining brightly, emitting both intense radiation and charged particles, creating not just an inward gravitational force but also an outward flux of particles of both matter and radiation.

Small gravitational perturbations or instabilities in the disk are racing to grow as large as they can and accrue as much mass as they can before the disk boils away.

Denser objects — as well as objects with larger mass-to-surface-area ratios — are relatively less affected by the outward flux of the star(s), but are simultaneously subject to resistance (and mass accrual) from the particles they run into.

The net result of all this is that denser bodies and larger bodies tend to migrate inwards, and that the young star system begins to act as though there’s a net buoyant force, pulling denser objects inwards and forcing the less dense objects to the new system’s outskirts.

Image credit: Dr. Avi M. Mandell, NASA / Goddard Space Flight Center.

This might sound like an amazing, unique story, but — at the end of the day — it’s all just straightforward physics, and these are the inevitable consequences of our physical laws. In addition to that, there’s a tremendous temperature gradient around the star(s), where objects very close to the star (inside the Soot Line) have complex molecules (like polycyclic aromatic hydrocarbons, or PAHs) photodissociate, and objects beyond the Frost Line can condense into ices, but not inside.

So, with that in mind, what is a typical star system — once it’s all grown up — going to look like?

Inside the Frost Line, there can be rocky planets, gas giants, and moons, where the density of these worlds will tend to decrease as we move away from the central star. Beyond that, there will typically be a belt of frozen particles accrued at the Frost Line, exemplified by the asteroid belt in our own Solar System. (Sorry, Giuseppe Piazzi; it wasn’t a planet, after all!) Outside of the Frost Line, it’s typically only going to be puffy, gas giant worlds (although mini-Neptunes count) that can clear their orbits and exist as planets-as-we-know-them, and finally there will be both a scattered disk and a large, spheroidal cloud of frozen planetesimals, all of much lower density than the inner, rocky worlds.

Measurements of the densities of worlds in our own Solar System confirm this picture, as do the first measurements of some exoplanetary systems.

So that’s what pretty much every star system is going to look like: worlds interior to a system’s frost line that can be a mix of rocky planets and gas giants, rock-and-ice asteroids at the frost line, gas giants exterior to the frost line, and mostly-ice-worlds beyond that in a scattered disk and in a spheroidal distribution beyond that.

So what does that mean for considering an object a planet in our Solar System, or in our experience in general?

It means that there’s a fundamental difference between the round worlds in hydrostatic equilibrium that have cleared their orbits interior to the frost line and all others, and it means there’s a fundamental difference between the gas giant worlds beyond the frost line and all others, and it also means that all the frozen worlds — both the ice-and-rock worlds at the frost line as well as the mostly ice worlds out beyond them — are ubquitous and super common.

If we make only the rocky worlds (and gas giant worlds) interior to the frost line planets, we have four planets. If we add in the gas giants beyond the frost line, we’d have four more, for a total of eight. If we decided to add in all the worlds in hydrostatic equilibrium — or with enough gravity to pull themselves into a sphere — we’d have something like an estimated 200 planets.

Mercury, Venus, Earth and Mars aren’t special because they’re spheres; they’re special because of where they are and what their formation history is! They’re special because of their densities, temperatures, atmospheres (or lack thereof, right Mercury?) and locations.

If I had my way, that’s what I’d teach everyone about the Solar System, and that’s why I think that eight planets is just the right number for our Solar System. You may (and many of you, I’m sure, will) disagree, but this knowledge and understanding is part of the driving force behind Pluto’s 2006 “demotion” from planetary status, not some vendetta against the cold, icy worlds of the Kuiper Belt, Oort Cloud and other locations beyond our Solar System’s frost line.

Our eight planets are all special, and all the gas giants and rocky-worlds-interior-to-a-frost-line are special in exactly the same way. The asteroids, Kuiper Belt objects and Oort Cloud objects may be special in their own way as well, but it’s a decidedly different way than these worlds that we presently call planets are. So remember that the next time you argue about what is-or-isn’t a planet; this is how the Universe really works, and everything else is just a name!

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Comments

Er, no. They are not “special in exactly the same way”. There’s a difference between the group of rocky bodies and all others, sure. There’s a difference between the group of gas giants and all others, sure. But the two groups themselves have nothing special in common. They do not cohere into a single exclusive group that excludes the other 200 planemos in our solar system . . . unless you deliberately and carefully pick a definition that has no purpose except to create a small list of “planets” that schoolchildren can memorize.

At which point, one might ask why we don’t adopt similar rules for “galaxies”, so that kids can memorize a nice convenient list of a half dozen to a dozen or so. Just because it wasn’t traditional to have a short list of them dating back to the ancient Greeks?

The ONLY ONE that you’re disagreeing with is (d) and the ONLY reason to disagree with it is if you want Pluto to be included in a list of planets of our sun.

Because dropping (a) would make it tens of thousands of objects. If you’re not worried about the length of the list, why include (a) in your definition? 100,000 names is no more immemmorable than 200+.

The Ursa Major Moving Group has dispersed to the degree that many stars in all directions around the sun are believed to have originated there, even if a small core remains in Ursa Major.
If this group gets the status of a cluster, we would be living inside its boundaries. Try to explain that to school kids.

Shouldn’t planetary formation take into account, pre-stellar ignition, stellar ignition and post stellar ignition, conditions. Also the impact of heat radiated from the forming planet upon the surrounding dust cloud (heat generated from impact, compression and radioactive elements).
Upon ignition a massive cloud wave front is pushed out to the edge of the system driven by new solar winds and expanding gases, favouring lighter elements and giving already existing stony worlds a massive coat, the further out the greater ( a balance between diffusion of stellar energy input, volume of dust cloud and rapid growth of the gravity well).
Forming planets also within themselves start to create conditions where denser elements are more likely to accumulate and lighter elements are driven off, with the bulk of the accumulation of volatile and light elements being post ignition when the massive much denser waver front passes.
As well as catastrophic solar system formation (planets out of sequence) as being the norm, no matter how disturbing rather, rather than adjusting system formation models to suit.
So the question remains, how much planetary accumulation occurs prior to stellar ignition and how it changes after stellar ignition, with only first stage suns being fusion ignited and 2nd, 3rd stage suns being fission ignited (access to newly created radioactive elements), which also significantly alters planetary formation. So sun colour allows modelling of likely solar systems.

Ethan Siegel, I love your work but afraid on this topic I have to respectfully disagree.

I think Pluto and the other ice dwarfs worlds count as planets as much as any other planets do and are all special in their own ways too.

All planets formed out of the swirling debris cloud from the largest to the smallest.

All planets, to me, are gravitationally rounded, not shining by core nuclear fusion and not moons of other planets. That’s how I see it and how I think the term makes most sense.

As for the number of planets – if there are over 200 of them then (shrug) there are over 200 of them. Why is that bad?

We already know there are (almost certainly) more than millions of planets out there round other stars. Should our solar system settle for a mere eight because of our counting bias? I don’t think so.

If Pluto was where Earth was we’d be in no doubt it was a planet.

If Earth orbited where Pluto was would we really quibble then? I doubt it.

What difference does a frost line really make when you have objects that are clearly one thing – round, fascinating, worlds in their own right -rather than any other – cometary nuclei, asteroids, etc .. ?

You have different objects forming of different substances at different distances sure, but why when one reaches the right level, right size, call it something else if its made of ice and rock versus just rock or mostly gas?

If a person is tiny and a crowd of similar small individual humans we don’;t say s/he stops being a person do we?

A small animal, a small plant, found in a herd or a forest or grassland of suchlike living things isn’t any different – they are still what they are – animal or vegetable not something else that they really aren’t.

So it is too, in my view for planets, sure they may be small, sure they may be in a zone full of similar planets but planets they still are.

If you disagree, please explain,exactly why you think that should not be considered the case?

PS. A dwarf star is still a star – indeed almost every star is a dwarf star including our Sun.

A “dwarf” variety of almost every plant or animal species is counted as still belonging to that species in science, regardless of how numerous the individuals in its flock / pack / herd / forest / shrubland / reef, etc .. might be.

The scientific convention and precedent thus seems very clear and seems to say that dwarfs are still planets /animals / plants, etc ..

Dwarfism is not an excluding factor from being ‘X’ whatever ‘X’may be!

Beyond the frost line is where worlds like Jupiter, Neptune and Pluto formed.

So, if we make that our divide then why count Jupiter and Neptune but not Pluto? Doesn’t make sense to me.

If we shift to cleared orbits – again that’s really problematic because no orbit is really that “clear” and if a rogue planet entered the solar system and entered a collision course with Earth or Venus would that stop either of them being planets? Surely not!

And what about a world that hypothetically forms right on the boundary – half outside the frostline and half within? Planet or not?

Also, if memory serves, we know that some comets formed at least partially close to the Sun from results from particles back from one of them (Wild 2 I think?) apparently formed in the inner solar system. So, could the same be true of Pluto and its kin? Could Pluto have formed at least partially in the inner solar system and migrated outwards? If so what does that do to the whole inside the frostline = planet; outside = not idea?

No, sorry Ethan, I just don’t buy this line of argument here. We may just have to agree to disagree.

“PS. A dwarf star is still a star – indeed almost every star is a dwarf star including our Sun.”

Irrelevant.

In Tolkein, Dwarves are a different race. Here in real life, they’re humans.

The words mean different things depending on where they’re being used.

So “Dwarf Stars are stars!” is not proof dwarf planets are planets.

Indeed your continual whining about that point is why the IAU nearly didn’t create the category “Dwarf Planet” because people whinging will use it to say the IAU are wrong. It’s why they didn’t do “Classical Planets”. And it may be the few people who wanted pluto argued into being a planet like the others argued for its inclusion: so they can say to themselves “It’s still REALLY a planet!”.

Dwarf star being a star is irrelevant to whether a dwarf planet is a planet.

Why?

Because of the definition of star and planet. Dwarfism in stars still mean they fuse elements in their cores under self-ignition. Since that is the definition of a star, they’re stars.

Dwarfism in planets mean they haven’t cleared their orbit, which is a requirement for being a planet, so dwarf planets are not planets.

Dwarfism in planets mean they haven’t cleared their orbit, which is a requirement for being a planet, so dwarf planets are not planets.

So, according to that neither Jupiter nor Neptune are planets as they haven’t cleared their orbits!?

As for dwarf planets being planets, they fulfill the IAU criteria bar the clearing the orbit part. So to say they aren’t a sub-type of planets seems a stretch. If they manage to clear the orbit, excepting trojans, do they then magically become real planets even if they stay out beyond the Kuiper belt?

“So, according to that neither Jupiter nor Neptune are planets as they haven’t cleared their orbits!?”

No, according to that definition, both Jupiter and Nepture are planets because they’ve cleared their orbits.

As for dwarf planets not being planets, they do not fulfill the IAU criteria in all cases. So to say they are a subtype of planets is wrong. If they managed to clear their orbits, then they will become planets, just like the protoplanetary disk becomes a planet when it coalesces into one and stops being a planet when it’s broken into many pieces that do not have the size to retain hydrostatic equilibrium.

Ethan’s explanation is untroubling to the IAU.

The only trouble are whiners who don’t want pluto to be ousted from planet status because, well, who the hell knows…

Ceres is a planet, and our solar system does not have only 8 planets, at least according to the equally legitimate geophysical planet definition. 19th century astronomers did not know that Ceres is in hydrostatic equilibrium and therefore a complex world that doesn’t belong in the category of asteroids and comets. It makes little sense to lump objects that structurally and compositionally are much more akin to the larger planets than to asteroids and comets with the latter category. It also makes little sense to require an object to “clear its orbit” to be a planet. We cannot look only at where an item is; we have to look at the individual item and what it is. These small spherical worlds are planets that have most of the same features the rocky planets have; the only difference is they are smaller.

The notion that we have to limit the number of planets in the solar system because we cannot have too many makes absolutely no sense. Memorization is not important to learning. Kids can be taught the different subclasses of planets and the characteristic of each subclass. After all, we don’t require kids to memorize the names of all rivers or mountains on Earth or the names of all Jupiter’s 67 moons.

The “IAU criteria” are not some gospel truth that should be taken as THE standard an object has to meet to be considered a planet. They represent one point of view in an ongoing debate. And they could result in the same object being considered a planet in one location and not a planet in another, something that makes absolutely no sense.

Why not instead recognize that some planets clear their orbits and some don’t? Similarly, some planets have no orbits to clear as they don’t orbit any stars (rogue planets). Yet structurally, they are planets.

Exoplanet systems clearly show that our solar system is not necessarily typical in its formation or layout. Every time an anomalous system is discovered, astronomers are sent back to the drawing board in determining how that system formed. There may very well be more than one way to make planetary systems. Otherwise, how do you explain hot Jupiters in close orbits around their stars? How do you classify giant planets in extremely elliptical orbits that travel through asteroid belts in those orbits? How do you determine what it means for an orbit to be “clear?”

Dwarf planets are special in the same way the larger planets are and are NOT special in the way asteroids, comets, and Small Solar System bodies are. The latter are frequently loose rubble piles shaped only by their chemical bonds. They are tiny and don’t have the complex structure that dwarf planets, which are small planets, have.

This isn’t about Pluto. It is about a dynamical versus a geophysical definition of planet and about whether the term planet should be kept narrow or broad. Given that Dawn has shown Vesta, which is not completely in hydrostatic equilibrium, to be more planet-like than asteroid-like, why not wait for the data from New Horizons and Dawn to show us just how unique and complex Pluto and Ceres are?

To bring up estimates is a red herring. There’s only a handful of dwarf planets. Making them a subclass of planets is endorsed by over 200 distinguished planetary scientists. Maybe even Frosty the Snowman, as well, who lives on the right side of your beloved Frost Line. Estimates are for realtors, not those making scientific definitions. Get a grip.

Yes, water freezes. There’s ice on Mercury, Earth, and Mars, genius. The Frost Line isn’t in the current IAU definition. Therefore, you shouldn’t support cutting off planets on its colder side, lackey that you are, correct?

If you wanna talk about the geo def, talk to the person who just defined it, genius.

The Frost Line is a silly concept by some blogger. It is not anything of note, in my opinion. Nor is the Soot Line. Soot is what comes out of your mouth during your vile rants and vulgar profanity-laced ravings.

To use the Front Line to keep Pluto and Ceres from being replanetized is a pathetic, desperation move. Knowing full well that the current IAU definition is short-lived due to it holes and the nefarious way in which it was passed on St. Bartholomew’s Massacre Day 2006, now Pluto’s problems are not only that it is “too small” but also that it is “too cold.”

Pathetic.

Mike Brown, as you know, when he first co-discovered Eris told he wife that it was a planet. Then, when he realized the IAU wasn’t going to call it a planet, he quickly changed his tune and went after Pluto in another desperation move.

When I correct you, I do not call you a moron. I expect the same courtesy, methane. Why don’t you grow up and stop idolizing grown men who behead dolls?

Dwarf planets are planets. Dwarf stars are stars. Dwarf galaxies are galaxies. Get over it, methane. Be consistent. Be a sane, logical person who does not resort to incessant insults and name-calling. Otherwise, go away. You are not contributing anything productive here until such time as you heed my advice.

Actually, for once you’re right: this indeed is the reason why your whines are irrelevant to the definition of planet. Because your opinion and “knowledge” on the subject is irrelevant and a “whatever”.

No, according to that definition, both Jupiter and Nepture are planets because they’ve cleared their orbits.

Both Jupiter and Neptune have their own sets of Trojan asteroids in their orbits. Their orbits are, therefoere, not cleared.. Just saying they have cleared their orbits doesn’t make it so, however much you may wish it to be true.

If they managed to clear their orbits, then they will become planets

So dwarf planets can become planets by changing one minor condition. Feel free to consider them not planets but you are stretching a minor thing into a major issue.

Even before it had almost completely cleared its orbit most people would have called Jupiter a planet not a dwarf planet.

“Clearing the orbit” does not mean there are no other objects in the orbit: it means that the body is large enough, with enough of a gravitational field, so that if other bodies are in the orbit they are deflected or pulled in: either way, they do not exert noticeable influence on the larger object’s path. Those other objects do not influence Earth’s movement: not so with the smaller bodies.

Remember, dean, mike knows fuck all, but is DAMN certain that the IAU are wrong, so anything is believed to that end.

Hell, the moronic arsehole kept bleating on about the “geophysical definition” then came up with a definition that WASN’T geophysical. When called up on it, changed the definition completely with the Jedi hand-wave of “That was not a complete[ly accurate?] definition”.

But if it wasn’t complete, why wasn’t it in the second attempt at defining it?

There should be, by definition, 9 classical planets. These are the objects in hydrostatic equilibrium discovered in the period before we had telecopes in orbit. When you talk of true planets, there are 8, with ~200 dwarf planets or planetoids. Yes, this is all semantics, but science is full of these. Why is Greenland not a continent? Why are Europe and Asia different continents? Why is a tomato a vegetable that has no business being in a fruit salad? What about an avocado? Don’t even get me started on true nuts vs. culinary nuts. Think peanuts, pecans, walnuts and cashews all belong in a single can marked “mixed nuts”? We use simple inaccurate classifications all the time. Leave the simple 9 planets alone. Call them classical and go wild with meaningful classifications for those who dig deeper. To me, that is part of the beauty of science. Like a wise ogre once said, it is like an onion.

Ethan is simply reiterating the dynamical definition of planet, which centers on where an object is. That is why he argues that objects beyond the Frost Line cannot be considered planets. I disagree because as a supporter of the geophysical planet definition, I cannot support a classification system that completely ignores what an object is and categorizes it solely by where it is. Not everything beyond the frost line is a tiny planetesimal. Some objects in the outer solar system are much larger and far more complex. Pluto has an atmosphere, and its density is closer to that of the rocky planets than to that of tiny KBOs. Ethan also repeats the argument that having “too many planets” somehow makes the term less “special.” I disagree with this as well. Does the fact that there are billions of stars in the galaxy and billions of galaxies in the universe diminish the words “star” and “galaxy?” I don’t think so.

The further a planet is from its parent star, the larger an orbit it will have to “clear.” That is an inherent bias of the dynamical planet definition. We know from exoplanet systems that not all solar systems form the same way and that there are many different patterns of planetary migration, many of which we do not yet fully understand.

Any classification that puts Jupiter and Earth in the same category but excludes objects like Pluto makes no sense. Earth has more in common with Pluto than with Jupiter. Both Earth and Pluto are rocky worlds rounded by their own gravity. Both have large moons formed via giant impacts. Both have nitrogen in their atmospheres, and both are geologically differentiated into core, mantle, and crust. In contrast, Jupiter’s composition is far more like that of the Sun, largely hydrogen and helium. It has no solid surface and has its own “mini-solar system” of moons and rings.

The geophysical planet definition is this: A planet is a non-self-luminous spheroidal body orbiting a star or free-floating in interstellar space (the latter referring to rogue planets).

There is no single legitimate definition of a planet. Wow, your constant repetition of the same statements does not make them anything more than one side in an ongoing debate. Science is not decided by a decree from a person or group who call themselves an “authority.” You should know that.

The mantra that there are probably 200 dwarf planets in our solar system is a red herring, a rhetorical device to cloud the issue. There is only a handful of known dwarf planets. Don’t drink the Kool-Aid.

“But your disagreement with the definition is worthless.
Sorry.
That’s just the way it is.
Pluto is not a planet.
They geophysical definition, never mind mikey’s ridiculous non-definition of it, doesn’t work.
The current definition does.
Pluto is not a planet.”

Your statements above are not science. They are an attempt to impose your view and only yours onto an ongoing debate. My disagreement is worthless–why? Because you say so? The fact that you write statements like this says more about your shortcomings in defending your position. The geophysical planet definition works just fine; that view is held by many scientists, not just by me and Mike W. Trying to “lay down the law” like a dictator does nothing to support your case. Please address the issues I raised regarding the problems inherent in the dynamical definition.

According to the geophysical planet definition, Titan, Ceres, and Pluto are all planets because they are celestial bodies in hydrostatic equilibrium orbiting a star.

The loudest voice should not get to win the arguement.
1) Who voted down the term classical planet? How was it “overwhemingly”?
2) I was not aware we had telescopes in orbit before the discovery and original classification of Pluto as a planet. Please list the name of the orbiting observatory that leads to your list of five plants.
3) You missed my larger point that all scientific classification is inherently messy. I purposely made an analogy to other fields of science. If you dismiss an analogy because it does not meet a specific definition (i.e. having to do with the IAU) you have missed the point of using an analogy.

If your facts are so strong why do you have to berate people in order to make your points? Please try to keep your replies to my above questions respectful or don’t bother to answer.

I was not aware that I was screaming. And you ignored all of my questions and jumped right into insulting me. You could have answered with facts, but you chose personal attacks. I am not sure what 10 day debate you are referring to, but the Great Planet Debate at Johns Hopkins in 2008 left no concensous.

If you don’t have to berate people to make your points, ask yourself why you chose in that very post to call me a moron and not answer my questions? Science advances with the debate of ideas, not personal insults. It is in my opinion a shame you berated your way into dominating this discussion. Have fun talking to yourself. I am done.

What is your problem with me saying there is only a handful of known dwarf planets?

You just want to disagree with everything for the sake of being disagreeable? It is working. Are you going to repeat the mantra about the 200 dwarf planets supposedly lurking beyond our ken? There could also be 865 Jupiters, too. Speculation of this kind is a cheap rhetorical device. Why stoop to that? Don’t you want to be taken seriously?

“That is why the definition was nearly unanimously passed by people whose job it is to deal with these things as scientists.”

Really? The majority of the 424 IAU members who voted on the planet definition are NOT planetary scientists but other types of astronomers. Planetary scientists are the people who most deal with planets, and they, not cosmologists or specialists in one of the many other areas of astronomy, are the ones whose job it is to define the term planet.

The reason I noted that Earth has more in common with Pluto than with Jupiter is to show the weakness of the IAU definition, which puts Earth and Jupiter in the same category but excludes Pluto.

“ASTEROIDS are rocky. That doesn’t make them planets.”

Asteroids are rubble piles loosely held together and shaped by their chemical bonds. In contrast, planets are shaped by their own gravity, which squeezes them into a round shape. Asteroids are not geologically layered and are not complex worlds with geology and weather the way small planets are. How is blurring the distinction between tiny, shapeless asteroids and complex worlds good science?

Yes, according to the geophysical planet definition, the Moon is a secondary or satellite planet. I don’t understand why this is a problem for you. If an object is massive enough to be squeezed into a round or near-round shape by its own gravity, it is a small planet. If it tiny and too small to be rounded by its own gravity, it is an asteroid or comet. SOHO is not a celestial body but an artificial satellite, which is why it is not a planet.

Pluto is estimated to be 70 percent rock. We don’t know much about its core, but that will change with the New Horizons flyby. Pluto’s atmosphere never completely freezes out to the point of being lost. Scientists now believe Pluto maintains at least some of its atmosphere throughout its 248-year orbit.

“Charon wasn’t formed like our moon was and Pluto didn’t gain it the same way.”

Charon is believed by scientists to have formed when a proto-planet smashed into proto-Pluto early in the solar system’s history, much the same way as Earth’s moon formed when a Mars-sized object impacted the Earth.

“Jupiter: Rocky core maybe 20 earth masses.”
At this point, that is speculation. It is still unclear whether Jupiter even has a solid core.

“What DID win the argument was the discussion over 10 days the definition of planet that the IAU then voted on that states that there are only 8 planets and that Pluto is not one of them.”

First, this is a scientific debate, and unlike political debates, it is not about winning and losing. Nothing “won” because debates are constantly reshaped as new and better information becomes available. Four percent of the IAU voted on the 2006 resolution, which was hastily thrown together in the last 24 hours of the General Assembly. An equal number of professional astronomers signed a formal petition rejecting that definition. Seven years later, many astronomers continue to reject it. It was never even close to being approved “unanimously.” Ninety-six percent of IAU members couldn’t vote because they weren’t in the room on a particular day, and no electronic or absentee voting was allowed. And immediately after the vote, one man who did vote asked for Pluto to be put back on the list of planets. Watch the video, and you will see this. He was told by Jocelyn Bell Burnell that it was too late; the resolution had already been adopted. This means he wasn’t clear about the resolution he had just voted for!

The list of planets was actually in the footnotes of the resolution, and if you watch the video from the beginning, you will see that there was a lot of confusion over whether the footnotes did or did not count as part of the resolution.

“Ah, that answers my question: no, you don’t know anything about pluto.”
I know Pluto is NOT an asteroid.
Is that what you say to everyone who disagrees with you?

45 in your delusions, methane. And why do you keep using the figure of 200?

Shall I name the known dwarf planets to you like Santa’s reindeer?

Ceres, Pluto, Charon, Haumea, Makemake, and Eris. You could also list the moons as satellite dwarf planets like Luna and Triton, Ganymede, et cetera. It does not come close to 45. What comic book did you find that figure in?

“Beyond the frost line is where worlds like Jupiter, Neptune and Pluto formed. So, if we make that our divide then why count Jupiter and Neptune but not Pluto?” -StevoR

It’s explained in the ATL text, Steve. Did you read it?

Yes I did indeed. Doesn’t mean I necessarily agree with what I read though.

“The frost line is not “the end of the planets”, it’s the end of the small rocky ones. Because past that point, water, the most common molecule in a protoplanetary disk, can stop around for a bit and be picked up and, being far more common than silicon et al, that means a lot more mass.”

Yes.

And?

The way planets form is fascinating – but it is NOT definitive.

Why the blazes should it be?

Is a person no longer a person if they were born by IVF or caesarian section versus “natural” birth?*

is a plant not a plant if it grows from cuttings instead of seed?

Course not!

Why then should a planet be a non–planet just because it formed beyond a certain distance?

Answer : It shouldn’t.

Besides how do we know or sure that Mars or even Earth and Venus didn’t start forming beyond the frostline and subsequently migrate inwards?

*Well, okay, it worked for MacDuff in the Scottish play and Eowyn in the ‘Lord of the Rings’ but that’s another two stories entirely! Besides Eowyn and MacDuff are definitely still classed as human / people / animals too.

@86. Mike Wrathell : “Do you (Wow) know what the word “known” means? Maybe that is your current problem.”

I would guess that “Wow” has a lot of problems – her / his trolling here being just one of them.

Did Wow eventually ever actually answer my questions on the other ‘Triton Kuiper King’ thread or elsewhere btw? Must go take a look I ‘spose.

Oh & Wow for the record – the number of currently known dwarf planets larger than Pluto is zero. Eris is about the same size and just a smidgin more massive. Makemake, Haumea, Sedna and others are smaller and the number of ice dwarfs currently known is from my memory much closer to fifty than two hundred. Not that it really matters anyhow.

Note : there are thousands of confirmed Jupiter mass & gas giant planets in the Milky Way and beyond. That sure doesn’t stop them being classified as planets. So then why should knowing about however many more ice dwarf planets make them any less planets either?

Hint : Trick question – it shouldn’t. There are thousands of exo-Jupiters and maybe hundreds of intra-Plutos and all of them are still properly considered planets given a reasonable (i.e. not the IAU’s!) definition of the word.

@62. Wow : “Yet you still whine and bitch that your definition isn’t taken when EVEN YOU don’t know what it is.

Among others, I have already suggested what my preferred definition of planet is and it is far superior to the IAU’s ridiculous one.

Again, a planet in my view is gravitationally rounded, so not an asteroid or comet nucleus, not self-luminous by nuclear fusion hence not a star and not directly orbiting another planet so not a moon – three straightforward, decisive tests.

I’ve also noted that other alternative definitions exist that would also count Pluto as a planet such as Ken Croswell’s here :

(Read that link yet, Wow? No? Refusing to look at evidence and arguments disagreeing with yours still Troll?)

So, that falsifies that rude and erroneous assertion of yours right there, Wow.

@51. dean :

““Clearing the orbit” does not mean there are no other objects in the orbit: it means that the body is large enough, with enough of a gravitational field, so that if other bodies are in the orbit they are deflected or pulled in: either way, they do not exert noticeable influence on the larger object’s path. Those other objects do not influence Earth’s movement: not so with the smaller bodies.”

Actually those bodies *do* influence earth’s orbit just relatively slightly. hence gravitational boosts. Yes the extent of the gravitational influence (perturbation) depends on a few other factors such as closeness of approach and velocity of the encounter but still there certainly is an effect.

So where do you draw the line? Who decides it and what if objects and cases that are right on that line?

Oh & where did you get that idea from that “clear” is exactly what you said as opposed to other ideas of what it means?

The fact that the IAU definition raises the needless superfluous* question of what “clear” actually even means is a major point against it given the key scientific principle of Occam’s razor.

Really? The majority of the 424 IAU members who voted on the planet definition are NOT planetary scientists but other types of astronomers.

And since the planetary scientist is working on the earth, not alien planets, meanwhile those planets are astronomical objects, and moreover this is an astronomical definition not a geographical one, the IAU members were field experts to judge.

Meanwhile you don’t even know about the planets you’re wibbling on about other than their names. See #64.

The reason I noted that Earth has more in common with Pluto than with Jupiter is to show the weakness of the IAU definition

Except as shown in #69, that statement is wrong and you only bring it up to “support” your complaint, but that statement, being false, does not support your complaint being valid.

Asteroids are rubble piles loosely held together and shaped by their chemical bonds.

Asteroids are rocky bodies. According to what you claim to be the geophysical definition of a planet, that counts as a planet. NOTHING about “rubble piles”.

Oh, and the chemical bonds do not hold the piles of rubble together. It seems like you don’t know even the basic science and refuse to let your ignorance impede your insistence.

Charon is believed by scientists to have formed when a proto-planet smashed into proto-Pluto early in the solar system’s history

No, Charon was assumed to be caught like Pluto was into a resonant circuit with Neptune as a kuiper belt object.

First, this is a scientific debate>/blockquote>

Not the way you do it. You have to have actual scientific knowledge and you don’t care for that: you make up sciencey claims and don’t really sweat actually knowing what the science is. See above.

debates are constantly reshaped as new and better information becomes available

Which is why the geophysical definition of a planet was abandoned: the better information showed that the definition was not capable of the job of defining planet status.

That’s why it took 10 days to come to the state where there was a proposal to vote on.

Four percent of the IAU voted on the 2006 resolution

100% were invited to. Not voting means that you don’t really have anything to say and defer to those who do. So yet another non-problem.

Ninety-six percent of IAU members couldn’t vote because they weren’t in the room on a particular day

If they’d wanted to vote, they could. They didn’t. And therefore didn’t stay. Yet more non-problem.

one man who did vote asked for Pluto to be put back on the list of planets

Yup, unanimity isn’t required in ANY democratic process. Another non-problem.

He was told by Jocelyn Bell Burnell that it was too late; the resolution had already been adopted

Yup. And when the “wrong pary” wins an election you have to either get enough votes to get a new election or wait until the next election to change it. You don’t get as a single person to whine and demand that the voters got the wrong answer and they have to do it again. Well you do, but you deserve being told “too late”.

Yet another non problem.

“Ah, that answers my question: no, you don’t know anything about pluto.”
I know Pluto is NOT an asteroid.

6 is a handful. Perhaps there are 39 possible candidates, but only 6 are dwarf planets as of this day. Sedna is not a dwarf planet. We don’t have enough data on it. Maybe Putin can send you there to report back on it.

If there’s one thing clearly shown is image no.8 (mass/density graph) is that there is no real way of distinguishing between objects in Sun’s orbit. It isn’t about size or mass or orbit only, it’s just terminology. If Europa i.e. was in it’s own orbit between Mars and Jupiter, it would be classified as a planet. Since it’s not, it’s Jupiter’s moon. If Pluto was i.e. the size of Earth or bigger, regardless how far it was, it would still be a planet in classification. Doesn’t really have to do with science per say.. it’s our own conventions. That simple.

I do agree however with those who think that the whole classification system should be perhaps a bit more scientific. It is a somewhat arbitrary at the moment IMO. But at the end of the day it’s just classification, people. You are arguing about if the line should have been drawn 2 cm lower, without any real reason.

Is same as arguing if one species of flowers should be categorized under rose family or tulip family… irrelevant really, as long as it’s there for everyone to see and admire 🙂

I didn’t say it’s not scientific. I said IMO should be MORE scientific as is now IMO a bit arbitrary.
At the moment we chose between 4, 8 or 200, depending on what to include/exclude in the definition. We chose 8. I would also choose 8 over 200. Like I said.. it’s classification. And all is good until one day we’ll find solar systems with perhaps 40-50 bodies in our definition of planet. And then we’ll change the definition again probably to keep to some managable number. Will our definition be based on science… of course. But still it has a lot to do with us ourselves. So it’s 50% social as well as 50% science.

@ Mike

sorry but I see no justice or injustice in all of this. Justice is a human notion, and since no human has been affected or harmed by this, what is the injustice? If someone i.e. owned a piece of land on Pluto and by demoting it to dwarf status lowered the land value, then you would have something to argue about. I can understand your sentimental attachment to Pluto… but that has nothing to do with justice or law or moral values.

@ Wow
more scientific in order to give a precise answer to a following question:
– if an object of Mercury size was found beyond Neptune with cleared orbit, would it be classified as a planet? I think it would. That’s our current definition. It is based on our solar system. What about if it’s was 0.98 size of Mercury.. or 0.995.. where do you draw a line? In other words we use the sizes of our own planets. When we discover more and more of smaller planets in other solar systems, I’m pretty sure the definition will change. But not because science changed or some universal things. We changed. Thus, like I said before, it’s 50% social.

You yourself wrote: “We chose not to use a different definition because that definition would include so many objects in our own system that the definition becomes useless.”… And I agree with this 100%. Just this is not science.. this is social. And there is nothing wrong with it. That is what I meant by arbitrary. If we as a society were a bit dumber we would choose the definition that gives only 4. If our brains were more of a chess type, we would love the definition that has 200 items. I don’t consider that 100% scientific.

“You yourself wrote: “We chose not to use a different definition because that definition would include so many objects in our own system that the definition becomes useless.”… And I agree with this 100%. Just this is not science..”

WRONG.

IT IS SCIENCE.

Science is the useful description of the reality we see around us, which is why, for example, “supernatural” claims or other claims that are inherently untestable are not scientific: they can produce no useful conclusion.

The way in which Pluto was demoted by the IAU by ramrodding was very unjust and political. It had nothing to do with science. The definition was designed with the specific intent to demote Pluto and the by-laws of the IAU were not followed so that only lackeys of the the Executive Committee’s cabal to demote Pluto were aware of what was going to go down. The few rational people who realized Pluto is and always will be a planet were grossly outnumbered as a result of this injustice.

Of course, to convince methane (Wow) of this would be like trying to convince him that living under a bridge is not the best abode for a human being. But, what the Hell, he likes living under a bridge, troll that he is, and who am I to judge?

No disrespect to amateur astronomers. The point being these 39 or so so-called dwarf planets out there have not been confirmed by the IAU which is the only international body that names things and confirms discoveries. So to speak of them as if they are a done deal is premature. Furthermore, to throw out the 200 figure is even more premature. It seems like a red herring, but, at best, it is speculation of some sort, based on what, probability? Is that what planetary science has come to?

I can do probability, too. I think it is probable, that you, methane, will be flying off the handle in the next 48 hours and making a troll of yourself once again.

There’s no point in arguing this issue- you’re arguing arbitrary definitions.

There can even be confusion and argument as to what constitutes a star- If it’s massive enough to fuse Hydrogen into Helium, there’s no question, but what about brown dwarfs that can fuse lithium only?

I love how distracted human beings are that distraction divorces them from what they actually are. Even the ugliest things have an intricate aspect of beauty and grandeur, however, and although distraction disgusts me, it turns out beautiful. (I would knock a psychiatrist cold with that punch. Ha, ha, ha.) This is coming from a non-human being, by the way, which is what I am. Every intelligence that is looking at this situation IS the situation. DUH! One IS the thing(s) one is looking at, perceiving and interacting with, the same as one is the perceiver/actor. The words of the article speak of elemental energies forming form itself, and I laugh constantly that human intelligence generally posits that primate intelligence is the only possibility in the vastness of space that harbors a superior form of intelligence. Read my lips: superior intelligence is everywhere and in all things. It’s Omnipresent. Just because one may not be intelligent enough to perceive particular kinds of intelligence “out there,” does not mean that intelligence is not “out there.” Kapish? Thus, quit being so distracted that you don’t know who/what you are. It entertains me too much! I laugh involuntarily. And that distracts me! You may have an infectious disease, and giving it to me, which threatens to turn me into the same thing(s) you are. But hell, on second thought, do whatever you will, and I will simply respond if it hits me just right. If not, I’ll remain disappeared and nobody will know I’m here. Chances are, most of my responses will be mirthful, though, because I think your condition is comedic, even though it may seem as much as life-threatening to you-all. I am laughing at you. Ha, ha, ha. This is not cruelty. My laughter is moved 100% by nature, and nature is not cruel. Part of why I laugh at human gesticulations/foibles is because of the posturing that creates such widely divergent contrasts between fantasy and reality that it just cracks me up. Nothing is more vital than I am, for instance, yet virtually everything I come across says that there is plenty more vital than I. What said things are doing is denying their own existence and it has nothing to do with me. There is no way I can deny my existence. It’s as close to me as the nose on my face. Yes, I have a nose on my face. Doesn’t everything? Ha, ha, ha. If not, I just have it become that way, only for me, because I like me. Even more, I love me. So, all you humans as would like to dot so, go ahead and deny your existence, and I’ll simply continue affirming mine until what, hell freezes over? Ha, ha, ha.

Earth was a captured COMET along with the other inner rocky planets. As ” high-falutin” as this presentation looks and sounds, it’s not necessarily correct. After all, animated charts and slick illustrations don’t prove anything. Even I could pay someone to make a cartoon where Bluetoe kicks Popeye’s ass and mops the street with his head, no matter how many cans of spinach he eats.

Ole Velikovsky was right about many things. Yes, he made some errors too, but who hasn’t? Even the iconic Jew, Einstein, made a few boners along his way.

No, WE didn’t choose 8. The astronomers of the world didn’t choose 8. A total of 333 of the 424 people in a room in Prague, who had already violated their own bylaws by bringing a last minute resolution before the General Assembly without first vetting it by the appropriate committee chose 8. And an equal number of professional astronomers signed a petition rejecting that choice. Most IAU members cannot afford to attend the whole conference or even part of the conference. Those that left early were misled into believing a different resolution, the one put forward by the IAU’s own committee, would be voted on. Dr. Owen Gingerich, who headed that committee, said in retrospect that had he known the General Assembly would vote on a different resolution thrown together at the last minute, he would have changed his plans to leave early. He didn’t know because this last minute change was an act of subterfuge by a tiny group that wanted to get their way.

What kind of scientific organization does not allow electronic voting? These astronomers write complex computer models; certainly one of them could create a secure electronic voting method so that those who couldn’t attend the General Assembly could still vote.

It isn’t 4, 8, or 200 planets. At the moment, it’s four (terrestrials) plus four (jovians) plus more (dwarf planets). The number of dwarf planets, like the number of exoplanets, is likely to remain in flux for a long time as new objects are discovered.

It is an injustice to mislead people into believing that a politically-motivated decision constitutes science. It is also an injustice to the general public to present only one side of an ongoing debate as fact when this is not the case.

All I got right now to add is that I am going with the solid count on dwarf planets. As they are confirmed by the IAU, my count will go up one at a time. There “may” be 200. There “may” be 300 or 400 or 433 in our solar system. But, a dwarf planet in the hand is worth two in the Oort Cloud or the Scattered Disk.

When they originally made Pluto not-a-planet, the rationale was that its orbit intrudes on that of the next planet in, which seems good enough to me, but doesn’t provide an opportunity to augment the C.V. like this article did.

No one said the IAU has to confirm the unnamed dwarf planets for them to be considered dwarf planets. What is needed, at least according to the geophysical planet definition, is sufficient observation to determine that these worlds are in hydrostatic equilibrium. In some cases, such as that of Sedna, there is uncertainty because the objects are so far away. If there is conclusive evidence an object is in hydrostatic equilibrium, then it is a dwarf planet, regardless of what the IAU says or doesn’t say.

On several occasions, I have observed elementary school teachers adopting the term “baby planets” to refer to the dwarf planets. Why not?

We do in fact enslave and abuse the Earth via pollution and a factory model that insists on ever-increasing yields with no rest period. That isn’t how the Earth works, and it risks depleting our soil and turning fertile areas into deserts. This has happened before. Humanity’s current interaction with this planet is extremely dysfunctional and leading towards a mass extinction and a harsher climate for most of the planet.

Technically, you are right, of course, Laurel. But I do not want Pluto, or any other dwarf planet to have an asterisk after it. Oh, we have 8 planets, and then there is Pluto*.

In a perfect world, the IAU would do its job and there would be no need for you to mention a possible need for a new international astronomical body.

Anyway, how many dwarf planets are there besides the 6 the IAU has confirmed in your estimation? Wow, aka “methane,” says there are 39 or so more. I did not think Sedna was a dwarf planet. I think the same problems Sedna has would also plague the other candidates, otherwise, the IAU would have confirmed them.

“What have they done to the earth?
What have they done to our fair sister?
Ravaged and plundered and ripped her and bit her
Stuck her with knives in the side of the dawn
And tied her with fences and dragged her down….”

“Is same as arguing if one species of flowers should be categorized under rose family or tulip family… irrelevant really, as long as it’s there for everyone to see and admire 🙂 ”

Except we’re at a level much more basic than the equivalent of the species /genus divide. This is more like arguing whether roses are animal mineral or vegetable!

Clearly they’re vegetable just as Pluto is clearly a planet not a star or asteroid! Saying otherwise is just, silly, really.

@99. Wow :

“the number of currently known dwarf planets larger than Pluto is zero”
WRONG.

Shouting in all caps doesn’t make you right y’know, Wow – it is you who is wrong in your unsupported deliberately provocatively rude assertions as per usual.

Eris is about the same size as Pluto in radius, slightly but not very much more massive.

So yeah, the number is zero or maybe just one depending on how you define “larger”.

Certainly there is no other ice dwarf that is significantly larger than Pluto in both size and mass yet discovered. After a long period of searching we haven’t even added any extra ones the same size as Pluto suggesting objects its size are still relatively rare.

@132. Wow :

“What is your source that says there are 45 known dwarf planets?”
Astronomers.

Really? Which astronomers exactly? Citation very much needed.

@142. Jan Vones :

“Until you want to start insisting that dwarf humans aren’t actually humans, I think you should admit that dwarf planets are planets.

That’s a lot more informative than making the silly claim a hydrostatically stable body orbiting the sun is not a planet.”

Exactly!

Informally, we already have divisions amongst planets both in our solar system and beyond based on their size, orbits and compositions.

The IAU definition, incidentally, in a further example of its idiocy and uselessness rules out planets beyond our solar system altogether – a ruling that is, of course, appropriately ignored by almost everyone when talking about planets outside our systems showing just how wrong the IAU definition actually is.

To be scientifically useful a definition needs to be applied to new and unknown cases and help work out what object X gets classified as. Starting with must orbit only our star out of the billions around shows a pathetic lack of imagination and sets up a ridiculously narrow limit.

For broad categories such as planets (or animal or plant or mineral categories) a definition really needs to be much more inclusive than the opposite.

To miss the point by such a colossal margin and fail to grasp what is meant by an analogy almost suggests you’re some kind of spambot rather than just a particularly willfully obtuse or contrary troll.

No planets aren’t people -but dwrafs of class X are all still consistently included in categories of object X. Being a small example of something doens’t mean that something isn’t something.

But then you really know that very well and are just posting here to irritate the rest of the people here aren’t you, Wow?

“When they originally made Pluto not-a-planet, the rationale was that its orbit intrudes on that of the next planet in, which seems good enough to me, but doesn’t provide an opportunity to augment the C.V. like this article did.”

Actually it was known almost from the start that Pluto’s orbit crossed that of Neptunes leading to speculation for a while that Pluto was in fact an escaped moon of Neptunes. This oddity was not considered cause for removing Pluto’s status at the time.

Nor is planets having crossing orbits considered valid cause for removing them from the planets category now because for example we know of at least one exoplanetary system, HD 45364 b & c where two gas giant worlds have a similar situation to the that of Neptune and Pluto and both worlds are acknowledged as planets -see :

The main “reason” people seem to have for removing Pluto’s planetary status seems to be because there are a number of similar worlds nearby that are almost or in the case of Eris pretty much exactly as big as Pluto.

Funnily enough, we don’t consider this cause for removing the planetary status of gas giants or rock dwarfs like Jupiter and Earth from planetary status when they too have similar worlds in their respective “zones” of our solar system. Although admittedly there are only three other examples of each as opposed to ten – perhaps fifty or more such worlds for the ice dwarf class of planet.

But still. It seems a matter of degree and principle here.

Having similar worlds nearby whether on crossing orbits or not shouldn’t define when something is a planet any more than having similar animals of the same species nearby makes an individual animal not an animal.

This for “Wow”s benefit is an analogy NOT a claim that planets are animals. I’ll spell it out for the troll here :

We don’t say Earth isn’t a planet even though it has Venus in a very close – especially as seen from the outer solar system – orbit nearby and these worlds have almost identical properties in many respects. (Eg. mass and diameter.)

We don’t say Neptune isn’t a planet even though it has Uranus in a similar orbit nearby and these worlds have almost identical properties in many respects. ( Indeed Neptune is physically smaller but more massive than Uranus so the question of which of those is”bigger” depends on what is meant!)

Therefore being consistent we have also surely got to say that we can’t say Pluto isn’t a planet even though it has Eris nearby and these worlds have almost identical properties in many respects. (eg. mass and diameter.)

IOW, having similar worlds nearby doesn’t stop a planet from being a planet which seems to be the main “argument” for removing Pluto’s planetary status.

The only difference is that there are more similar worlds like Pluto than there are like Earth and Neptune but this is not,I think, good or sufficient cause for reclassification because its just a degree in number not a fundamental property or definitional problem. It doesn’t really matter because for example if we had ten Earths nearby we may describe our space as being crowded with earth-like planets but we’d hardly say they were all therefore asteroids instead!

“Actually it was known almost from the start that Pluto’s orbit crossed that of Neptunes leading to speculation for a while that Pluto was in fact an escaped moon of Neptunes. This oddity was not considered cause for removing Pluto’s status at the time.”

It was thought that Pluto was much more massive, and it was the great mass of the presumed pluto that made it a “Planet”.

Moreover, the larger asteroids were likewise not known to have a co-habiting cloud of other similar bodies, later called the asteroid belt. However, on finding one, that became the reason to change the (currently 23) planets back to 8. Nobody complained.

But Pluto, being found smaller than expected by a large factor and then finding it exists with many other similar bodies, such a collection being called the Kuiper Belt has meant that the astronomers, as they did with the Asteroids, created a classification of non-planet for the previously presumed planet Pluto.

“Neither of which was the claim that I said was WRONG. So irrelevant. Making a statement never made as if it were some form of referral to a previous statement is called lying, steve. It’s naughty. Stop.”

Your claim was and I quoted you directly : “the number of currently known dwarf planets larger than Pluto is zero – wrong.”

The error – the wrongness here – was yours because Eris and Pluto are the same size (diameter) to within the error bars. It is true as I and others have said – with that supporting evidence – that there aren’t any dwarf planets larger than Pluto – the number is zero. So, no lie on my part Wow, just an explanation and elaboration showing why your trollishly capitalised and unsupported claim of “wrong” was itself wrong.

“Formally, we have planets. 8 of them. And many Dwarf Planets of which Pluto is one. Apparently, this is not allowed to stand, however.”

It isn’t allowed to stand because there are very good reasons why your above asserted but unsupported claim of only 8 planets is wrong and why dwarfs planets logically must count as planets as much as giant and other ones.

“Which is why the geophysical defition fell down. Why the definition the IAU gives was accepted by those able to test whether the definition met those criteria.”

Er, really? No. My point was the IAU definition excluded the main source of such new cases to which we have to ask the question – planets found outside our solar system . So no the IAU definition isn’t good at all there and falls down completely on that point. Exoplanets are also planets no less than those in our solar system. A definition that excludes them isn’t scientifically useful when the field of exoplanets is now one at the cutting edge of astronomy!

But you refuse to accept those criteria unless it lets Pluto be a planet.”

I’d also reject any definition of animal that say a dog isn’t an animal and any definition of a plant that says a rose isn’t a plant – because any such definitions would clearly be ludicrously flawed.

“To miss the point by such a colossal margin ..” [-StevoR]
There was no point. Only rhetorical shiboleths of the whiney bunch.Dwarf planets are not planets. Dwarfism in humans is not a case of a human not clearing its orbit. End of.” -Wow

And here, yet again, you deliberately miss (or pretend to miss) the point completely, Wow. Because you are a troll.

No its not rhetoric, its logic.

Its also nomenclatural consistency which is important for understanding and teaching science.

Something that is a dwarf or small member of category X remains a member of category X – it isn’t excluded from that category simply on the basis of its size.

This applies to animals, plants and everything else -including planets.

That’s not merely my assertion that’s how the field and its terminology works. We don’t exclude dwarf stars from counting as stars, we don’t exclude dwarf plants from counting as plants, so excluding dwarf planets from counting as planets would be and is illogical, inconsistent and wrong.

What part of this do you fail to comprehend (or will you pretend to fail to comprehend for trollings sake) exactly Wow?

“To miss the point by such a colossal margin ..” [-StevoR]
There was no point. Only rhetorical shiboleths of the whiney bunch.Dwarf planets are not planets. Dwarfism in humans is not a case of a human not clearing its orbit. End of.” -Wow

And here, yet again, you deliberately miss (or pretend to miss) the point completely, Wow. Because you are a troll.

No its not rhetoric, its logic.

Its also nomenclatural consistency which is important for understanding and teaching science.

Something that is a dwarf or small member of category X remains a member of category X – it isn’t excluded from that category simply on the basis of its size.

This applies to animals, plants and everything else -including planets.

That’s not merely my assertion that’s how the field and its terminology works. Hence we don’t exclude dwarf stars from counting as stars, we don’t exclude dwarf plants from counting as plants, so excluding dwarf planets from counting as planets would be and is illogical, inconsistent and wrong.

What part of this do you fail to comprehend (or will you pretend to fail to comprehend for the sake of trolling to annoy others here) exactly Wow?

Thanks, Wow, i learned so much from your comments here, about planets and cosmos and that there are so many people who wont try to understand, just wont think what they are, minds clouded, shouting. Thank you!

“Q: How many dwarf planets are there?
A: Currently there are five objects accepted as dwarf planets.”

Not saying there are only. Key words:

Currently accepted.

But look beyond the mine you want so hard to be all there is:

Q: Are there additional dwarf planet candidates currently being considered?
A: Yes. Some of the largest asteroids may be candidates for dwarf planet status and some additional dwarf planet candidates beyond Neptune will soon be considered.

Q: When will additional new dwarf planets likely be announced?
A: Probably within the next few years.

Q: How many more new dwarf planets are there likely to be?
A: There may be dozens or perhaps even more than a hundred waiting to be discovered.

Hmm.

Seems like the IAU say there are perhaps more than a hundred out there. And indeed the wiki link that Steve petulantly refused to read indicates that there are indeed many MANY more than a hundred.

Odd how you did not link to support your claim, which is not only because it destroys your “argument” that there are only a handful of dwarfs, but also because it shows that your attribution was false.

Even more amusing is Dai wibbling on with how you’re right, mikey, but didn’t actually appear to read it at all before arriving at the conclusion he so desperately loves to prove.

Not good enough Mike. You should have said “confirmed” or “named”, anything the unambiguously defined your position. Wow has asked you a question similar to “What was the largest island in the world before Australia was discovered, and you have given the moronic answer “Greenland”. He would rather argue semantically to prove himself “right” than let the argument move on to ground where he exposes himself to the risk of being wrong, or even worse, exposing the gaps in his understanding.

Someone besides Mike Brown needs to confirm things, methane. The IAU is the main group. Unfortunately, sometimes they let the worst part of human nature affect their actions, but they still are the body that names and confirms, so I don’t have a lot of choice. I just wish they would do their fucking job without the bullshit.

It was discovered on February 17, 2004 by Michael Brown of Caltech, Chad Trujillo of the Gemini Observatory, and David Rabinowitz of Yale University. Precovery images as early as November 8, 1951 were later identified

Aaaaaw.

PS, odd that you now defer to a decision by a selected committee on what constitutes a dwarf planet, planet, SSB and so on. I bet you won’t be consistent in your assertions, though, will you.

I don’t know who you are, Wow, but your manners are boorish, at best. SEVERAL people have attempted to have a rational, reasonable discussion with you, which you responded with insults, profanity, and an authoritarian demand that YOUR understanding of the IAU decisions about Pluto mean.
After New Horizons flew past Pluto last year, the IAU was willing to concede it as a planet again.
Then, REALLY confuse the mix, there is now evidence of another planet, larger than Earth, orbiting out beyond the Oort Cloud, perpendicular to the other planetary orbits. This is one of MANY advantages that science has over religion. With religion, you have to fit new data or observations to preexisting definitions, while science changes definitions when new data presents. Stop being so close minded and insulting to those who disagree with you, and instead try to have a grown up discussion for once.

The “tone troll” is a real critter. They are the most common subspecies of Internet troll, mostly harmless but super annoying, and easy to spot in the wild: they complain about the tone of a message, rather than its substance. They fixate on the allegedly poor attitude of anyone who challenges them.

I neither ask you to like it nor emulate it.

You are all for free speech but only the speech mannerisms you like. Mannerism is part of speech, retard.

You have NO proof of your claims, yet feel free to call people names, now calling me moron and liar. You think I’M the troll? Your laughable ignorance chows that you are both a troll and a bully.
Remember that free speech is NOT free from consequences. If you were face to face with me, talking as you have to the people on this page, your LEAST consequence would be a broken nose and fat lip. This is not your blog, you are not god and you are not the head of the IAU, so you don’t get to decide what definitions of “planets” people use. Get off your high horse, and deal with people intelligently, or get out of your mom’s basement and get a job.

I didn’t bother to include a link, since that wasn’t the point of my comment. The point was, and still is, that rather than discuss things with people RATIONALLY, you immediately start throwing insults. That was your response to me. From my first comment, rather than even trying to debate the points, you called me a moron. And your most recent comment about burning my house down proves the point that you are nothing more than a cheap-ass bully. Even through the course of “discussion” with Mike Wrathell and Laurel Kornfeld, you never once cited any actual proof of your stance, you just called them names. You don’t get to act like a chimp throwing shit and then claim the moral high ground.
Even when others made the comment that the two of you would have to “agree to disagree” you hurled insults. That sort of authoritarian power-over does nothing to advance mankind’s knowledge of the universe. It only seeks to subjugate others to your beliefs.
Now you are pissed at me for calling out your dishonesty and bullying. Good, stay pissed, your opinion are easier to discount when you act like Trump.

What? Without evidence you have an evidentless claim. And a tone troll.

So we can discard the claim that the IAU is considering Pluto a planet by any measure, and that the topic of the thread “Why there are (and should be) eight planets in the Solar System ” was necroed by you to whinge at someone clearly your superior about something you have needlessly invested your self-esteem into.

No, I was not “Tone trolling” I was calling out a bully who is too big of a pussy to do anything other than insult people.
As for you being my superior, you are not even superior to dog shit, let alone any human being.
As for whether the solar system should have 8 planets or not, more recent discoveries, like “Planet Nine” should put that to rest.

(three links to information about Planet Nine, in case you want to bitch that I didn’t prove that either)

Granted, that is a two and a half year old article, not post-New-Horizons, but even in October 2014, members of the IAU WERE discussing re-designating Pluto as a planet. As for the assertion in the article that there were “no plans to put it on the agenda” that means NOTHING. Many things end up on business or government agendas that nobody planned on adding.

Hey, moron, you COULD have just said that you think that Pluto should remain a planet. No evidence would be required, then. But, no, you decided to make shit up, then when asked (nicely by the bunny, proving that being polite to you is not a working strategy and therefore irrelevant to you), you blabbered about how it wasn’t your point.

The tone argument (also tone policing) is a logical fallacy that occurs when an argument is dismissed or accepted on its presentation: typically perceived crassness, hysteria or anger. Tone arguments are generally used by tone trolls (esp. concern trolls) in order to derail or silence opponents lower on the privilege ladder, as a method of positioning oneself as a Very Serious Person.

The fallacy relies on style over substance. It is an ad hominem attack, and thus an informal fallacy.

“do anything other than insult people.”

100% provably false. This claim is liable to the “black swan” created, as it is, by confirmation bias and thoughtlessness from those whose mental capacities are unable to believe anything they were not previously open to believing.